Hydrocarbon conversion process



United States Patent HY DROCARBON CONVERSION PROCESS George R.Donaldson, North Riverside, Ill., assignor to Universal Oil ProductsCompany, Chicago, 111., a corporation of Delaware No Drawing.Application May 29, 1950, Serial No. 165,107

8 Claims. (Cl. 196-50) This invention relates to the catalyticconversion of hydrocarbons. It is more specifically concerned with amethod of reforming hydrocarbon fractions boiling approximatelywithinthe gasoline range.

Recently, a superior reforming catalyst has been developed, saidcatalyst comprising palladium or, preferably, platinum and alumina asthe, principal constituents and frequently containing minor amounts of ahalogen, particularly fluorine or chlorine. Catalysts of this type arecapable of increasing the octane number of hydrocarbon stoclts such asstraight-run gasolines and naphthas to values that are substantiallyhigher than those that ordinarily can be reached by thermal reforming.In addition, the yield-octane number relationship is much better thanare the corresponding relationships obtained in either thermal reformingor in most of the prior catalytic reforming processes. It has been foundthat by an appropriate selection of operating conditions and by charginga feed stock of relatively low end point, these catalysts can be usedfor a number of weeks or months without regeneration. HOW6V61,lf the endpoint of the charge stock is relatively high, orif the charging stockcontains minor traces of impurities, such as nitrogen compounds, whichtend to deactivate or poison the catalyst, the rate of catalystdeactivation is greatly accelerated. In order that this process beeconomically attractive it is desirable that it besubstantiallynonregenerative. I have invented a process by means ofwhich greatly increased catalyst life is obtained with poor stocks aswell as with good stocks.

It is an object of this invention to convert gasoline boiling rangehydrocarbons to more valuable products.

Another object of this invention is to reform low octane numberhydrocarbon fractions to products of higher octane number.

Still another object of this invention is to reform in substantiallynonregenerative operation in the presence of platinumorpalladium-containing catalysts gasoline fractions that tend torelatively rapidly deactivate said catalyst.

In one embodiment my invention relates to an improvementin theconversion of a hydrocarbon charge stock in the presence of a catalystselected from the group consisting of platinumand palladium-containingcatalyst at conversion conditions at which the charge stock tends todeactivate the catalyst, said improvement comprising processing saidstock until the catalyst has lost a measurable amount of activity,discontinuing the processing of said charge stock and substitutingtherefor a hydrocarbon charge stock which exhibits less tendency todeactivate the fresh catalyst, processing said latter stock until atleast a part of the lost activity has been restored, and thereafterdiscontinuing the processing of said latter stock and resuming theprocessing of said first stock.

In a more specific embodiment my invention relates 2,723,946 PatentedNov. 15, 1955 ice to an improvement in the reforming of a hydrocarboncharge stock boiling approximately within the gasoline range and havinga relatively high end point in the presence of hydrogen and aplatinum-containing catalyst at reforming conditions at which the chargestock exhibits a substantial tendency to deactivate the catalyst, saidimprovement comprising reforming said stock until the catalyst has losta measurable amount of activity, discontinuing the reforming of saidcharge stock and substituting therefor a normally liquid hydrocarboncharge stock of lower end point which exhibits less tendency todeactivate the fresh catalyst, reforming said latter stock until atleast a part of the lost activity has been restored, and

' thereafter discontinuing the reforming of said latter stock andresuming the reforming of said first stock. I

In another specific embodiment my invention relates to an improvement inthe reforming. of hydrocarbon charge stocks boiling approximately withinthe gasoline range and having an appreciable nitrogen compound contentat reforming conditions at which the charge stock exhibits a substantialtendency to deactivate the catalyst, the improvement which comprisesreforming said stock until the catalyst has lost a measurable amount ofactivity, discontinuing the reforming of said charge stock andsubstituting therefor a normally liquid hydrocarbon charge stocksubstantially free from nitrogen compounds which exhibits less tendencyto deactivate the fresh catalyst, reforming said latter stock until atleast a part of the lost activity has been restored, and thereafterdiscontinuing the processing of said latter stock and resuming theprocessing of said first stock.

In the hydrocarbon reforming processes employing a catalyst comprisingplatinum and alumina or palladium and alumina, the hydrocarbon reactantto be converted is preheated and, together with hydrogen, is contactedwith the catalyst. As is usual in catalytic processes of this type, thehydrocarbon conversion reaction ordinarily is accompanied by a foulingreaction which causes deposition of carbonaceous material, hereinaftercalled carbon on the catalyst. The presence of the deposit lowers theactivity of the catalyst and in the usual operation a point is reachedat which the elfectiveness of the catalyst is so low that it must eitherbe discarded and replaced with fresh catalyst, or the activity of thecatalyst must be restored by the removal of the carbon by combustion.Both methods are expensive, and it can be readily seen that substantialeconomic and operating advantages would accrue if it were possible tohinder or retard carbon formation, or remove carbon formed during theprocessing of the hydrocarbon.

I have found that the useful life of the catalyst can be greatlyincreased if a charging stock that exhibits a low tendency to foul orcarbonize the catalyst is periodically substituted for the normalhydrocarbon charging stock that exhibits a greater tendency to foul thecatalyst.

It has been observed that hydrocarbon fractions possessing relativelyhigh end boiling points produce a considerably larger amount of carbonin a given amount of time than do hydrocarbon fractions having lower endboiling points. Thus, for example, the catalyst carbon production ratewith a 300400 F. straight-run naphtha is many times higher than is thecarbon production rate at equivalent conditions With a 300 F.straight-run naphtha. I have found that if I reform a relatively highboiling hydrocarbon fraction in the presence of a palladiumorplatinum-containing catalyst, thereby depositing an amine ciable amountof carbon on the catalyst, and thereafter reform a lower boilingfraction with the same catalyst, that there "is not merely a decrease inthe rate at which carbon is deposited during the processing of thelastnamcd fraction, but that there is an actual decrease in the amountof carbon on the catalyst. This decrease in the carbon content of thecatalyst results in at least a partial restoration of the catalystactivity. Consequently, it is possible to again switch back to thehigher boiling fraction and obtain an appreciable further amount ofconversion therewith. Briefly then, it can be seen that I am able toprocess a greater amount of higher boiling charging stock with a givenamount of catalyst by alternately processing higher boiling and lowerboiling stocks, than would be possible if I processed only the higherboiling fraction.

' A particularly useful application of my invention involves separatinga normal wide boiling hydrocarbon reforming stock into, for example, ahigher boiling fraction and alower boiling fraction and alternatelysubjecting said fractions to reforming in the presence of a catalystcomprising palladiumor platinum-alumina. Each fraction can then beprocessed under the conditions most favorable for a good yield-octanenumber relationship for that particular fraction. In addition, theprocessing of the lower boiling fraction removes a certain amount of thecarbon deposited 'on the catalyst during the processing of the higherboiling fraction. With this type of operation I can obtain "markedlyincreased overall catalyst life as well as a superioryield-octane numberrelationship. I

' iknother type of hydrocarbon reforming charge stock that tends todeactivate catalysts of the type herein described are those hydrocarbonfractions that possess an appreciable nitrogen compound content. Thenitrogen compounds appear to temporarily poison the catalyst, therebydeactivating the same. The deactivation does not appear to 'be-due todeposition of carbonaceous material on the catalyst, since the rate ofcarbon formation with such stocks frequently is appreciably lower thanit is with nitrogen-free stocks. I have found that if a catalyst thathas become at least partially deactivated through the reforming of ahydrocarbon "stock containing nitrogen compounds, is used for thereforming of a nitrogen-free charging stock, the activity of thecatalyst is largely restored. Therefore, when it is necessary to processa hydrocarbon stock containing an appreciable nitrogen compound content,such "as astraight-run gasoline from the 'Los Angeles Basin, Ialternately process a stock that "is substantially free from nitrogencompounds. lnthis way 'I am able to process -'a much larger amount ofthe nitrogen-containing stock thanwou'ld otherwise be possible.

The hydrocarbon stocks that may be converted in accordance with myprocess "comprise hydrocarbonfractions containing saturatedhydrocarbons, particularly naphthene's. The preferred stocks are thoseconsisting essentially of naphthenes and paraflins, although in somecases aromatics and/orplefin's also may 'be present. Thispreferred classincludes straight-run gasolines, natural gasolines, and the like. On theother hand, it frequently is advantageous .to charge t-hermallyorcatalytica'lly cracked gasolines, particularly higher boiling fractionsthereof to my reforming process. If a cracked gasoline or fraction ischarged, it often 'w-ill-b'erprocessed in admixture with astraight-runfraction. The gasoline may be .full boiling range .gasolinehaving an initial boiling :point of 'from about "50 to about 100 .F. andan end boiling point within the range of from about 325 to about 425 F.,or itmaybe'a selected fraction thereof which usually will be a higher'b'oili'n'g fraction, commonly referred to as naphtha, and generallyhaving an initial boiling point within ther'ange of from about 125 toabout 250 F. and an end boiling point within the range of from about3'50" F. to about 425 F.

, Ihe hydr'ocar bon :stock that 1 use to 'at'least -partially restoretheactivity of theusedcatalystshould'be 'one that exhibits less tendencythan -the first-used stock to deactivate the catalyst :at substantiallythe "same operating conditions or, preferably, at conditions to givesubstantially the same octane number, when employing fresh catalyst. Forexample, if stock A is reformed over platinumalumina-combined halogencatalyst until there has been an appreciable loss in catalyst activity,stock B can be used to restore at least a portion of said lost activityif stock B causes less deactivation of fresh platinum-aluminacombinedhalogen catalyst than is brought about by stock A at conditions to givereformates of approximately the same octane number. p

The reforming catalyst that may be used in my process is selected fromthose catalysts, comprising at least one refractory oxide composited orassociated with platinum or palladium, that are capable of promotinghydrocracking of paraffins and dehydrogenation of naphthenes. Apreferred type of catalyst that falls in thisv category is described inU. S. PatentNo. 2,479,109, issued August 16, 1949. These catalystscomprise alumina, platinum, and combined halogen, especially combinedfluorine and combined chlorine. They are prepared by forming a mixtureof alumina and a halogen compound, the halogen being in an amount offrom'a'bout 0.1% to about 1.0% "by weight of said alumina on a drybasis, and thereafter compositing about 0.1% to about 1.0% platinum withthe mixture, and subsequently heating the composite.

Another group of catalysts that maybe used in the present processcomprises a cracking component and a metal selected from the groupconsisting of platinum and palladium. The cracking component ordinarilywill comprise silica and at least one other metal oxide, usuallyselected from the group consisting of alumina, zirconia, magnesia, andthoria. Another type of cracking component that may be used in thesecatalysts comprise alumina-boria composites. These catalysts are made,for example, by drying a composite of silica hydrogel and aluminahydrogel and thereafter incorporating into the dry composite a metalselected from the group consisting of platinum and palladium in an.amount of from about 0.1% to about 1.0%. Further details concerning thepreparation of catalysts of this type will be found in U. S. Patent'No.2,478,916.

Hydrocarbon reforming operations carried out in accordance with myinvention ordinarily will be conducted at temperatures of from about 600'F. to about 1000" F. ii the catalyst comprises a cracking component anda metal selected .from the group consisting of platinum .and palladium.If the catalyst comprises platinum-aluminacornbined halogen, thetemperature ordinarily will lie within'the range of from about 750 F. toabout l000 .F.

The pressures at which my process will be conducted will lie within therange of from about 50 to 1200 p. s. i., a total pressure of at least250 lbs. ordinarily .is preferred. The 'weight "hourly space velocity,defined as the weight of hydrocarbons charged per hour per weight ofcatalyst in -the reaction zone, should lie within the range of fromabout 0.2 to about 40. T he amount of hydrogen charged along with thehydrocarbons usually will be from about 0.5 to about 15 mols per mol ofhydrocarbon. However, with certain types of charging stocks and incertain types of operations, sufficient hydrogen is produced in situ sothat there is no necessity for charging external hydrogen.

The following example is given to illustrate my invention, but 'it isnot given for purposes of limiting the generallyibroad scope of saidinvention.

.A Mid-Continent straight-run gasoline was fractionated into a lower anda higher boiling fraction. The lower boiling fraction had a boilingrange, in the ASTM dis:

The operating conditions and results are shown in the following table:

It can be seen that the reforming ofthe lower boiling straight-rungasoline fraction over the used catalyst low- T able I Run No- 1 2 3 4Catalyst Fresh Fresh Fresh Fresh 190-350 350400 190-350 350-400 350400350-400 FEP FEP FEP FEP FEP FEP Length of Run, Hours 65 65 22 192Operating Cond.:

Average Oat. Temp., C 456 457 456 456 Pressure, p.s. i. g 500 500 500500 Liquid Hr. Space Veloeity. 2.0 2. 2. 0 2. 0

Hz/Chg. Mol Ratio 3.2 3.6 3. 5 3.4 Reiormate Yield, Vol. Percent 92.2-93. 8 91. 9-93. 3 92. 2 93. 994. 9 Reformate Octane Nos.:

F-2 Clear- 78. 0-76. 2 76. 4-69 2 75. 8 66. 2-65. 8

F-2-l-3 cc 86. 7 74. 4

F-l Cle r 84. 7 81. 7-75 4 81. 7 71. 170.8

F-l+3 cc. TEL/gal 94.7 91. 987 7 92. 2 85. 7-85. 2 Carbon on Catalyst:

As Charged, Wt. Percent.... O 0 0 0 As Removed, Wt. Percent 0. 78 4. 993. 44 8. 42

The longer runs were divided into periods and reformate inspections andyield data were obtained for the various periods, which accounts for theranges given in the table. However, complete analytical data were notalways obtained for each period, hence such values as were determinedare reported.

A comparison of the results of run No. l with those of run No. 2,showsthat the higher boiling stock produced more than 6 times the amountof carbon that was produced by the lower boiling charge stock in thesame length of time. A comparison of runs 2, 3 and 4 shows that theamount of carbon deposited on the catalysts in creases with increase inprocessing time. The activity decline of the catalyst is shown by theabsolute octane numbers of the reformate as well as the variationsduring the run. The variations or ranges are not strictly comparablebecause the time intervals in each run during which reformate wascollected and the octane number thereof determined varied somewhat fromrun to run. However, in general, it can be seen that not only is thequality of the reformate produced fromt he higher boiling charging stocklower than that produced from the lower boiling charging stock, but alsothat the rate of decline in quality, which is a measure of the rate ofdecline of catalyst activity, was greater in the runs in which thehigher boiling material was reformed.

The catalyst from each of the foregoing runs was used,

ered the carbon content of said catalysts. The restoration of theactivity accompanying the decrease in the carbon content is shown by theincrease in the octane numbers in the reformate during the runs.

The data in the foregoing tables show that platinumalumina-combinedhalogen catalyst that has been substantially deactivated during theprocessing of the relatively high end point reforming charge stock, canbe reactivated at least in part by further reforming with said catalystof a lower boiling charging stock. When such partially reactivatedcatalyst, as was recovered from runs 5, 6, 7 and 8, is used for theadditional processing of higher boiling fractions, it is found that thecatalyst exhibits increased activity in such operation.

I claim as my invention: 1. In the reforming of a hydrocarbon chargestock boiling approximately within the gasoline range and having arelatively high end point in the presence of hydrogen and a catalystcontaining a metal of the group consisting of platinum and palladium,the method which comprises reforming said stock until the catalyst haslost activity, discontinuing the reforming of said charge stock andsubstituting therefor a normally liquid hydrocarbon charge stock oflower end point, reforming. said latter stock in the presence ofhydrogen until at least a portion of the last activity has beenrestored, and thereafter discontinuing the reforming of said latterstock and resuming l r I without regeneration or further treatment, inthe reformthe reforming of said first stock. ing of a -350 F. end pointPennsylvania straight- 2. The process of claim 1 further characterizedin that run gasoline. The operating conditions and results of saidnormally liquid hydrocarbon charge stock comprises these runs are shownin the following table: The catalysts a straight-run petroleum fraction.from runs 1, 2, 3, and 4 were used in runs 5, 6, 7, and 8, r: 3. Theprocess of claim 1 further characterized in respectively. that saidcatalyst comprises platinum and alumina.

Table 11 Run No 5 6 7 8 Catalyst Fresh Fresh resh Fresh Charge FEP FEPFEP FEP FEP Length of Ron, Hrs 72 72 74 Operating Conditions:

Catalyst Av., 0. 466 465 464 Pressure, p. s. i. g... 700 700 700 LiquidHr. Space Vel. 4.0 4. 0 4.1

H2/Chg.1\TO1 Ratio. 5. 4 5.1 5. 2 Reiormate Yield, Vol. Percent 96.195.8 95. 8 Retormate Octane Nos:

F-2 Clear 66. 3-6110 670459. 1 60. 2-64. 2

F-2+3 cc. TEL/gal 83. 1-84. 6 s3. 1 80.8

F-l Clear 70. 3 71. 0-74. 2 63. 3-66. 8

F- 1+3 cc. TEL/gal 86. 3 87. 0 s7. 6 so. 8454. 2 Carbon on Catalyst:

As Charged, Wt. Percent... 4. 99 3. 44 8. 42

As Removed, Wt. Percent. 4.37 2. 96 7. 07

-4. '-Ihe process-of claim 1 further characterized in that said-catalystcomprises alumina containing from about 0.1% to about 1.0% platinum andfrom about 0.1% to about 1.0% combined halogen.

5. The process of claim l further characterized in that 7 said catalystcomprises alumina containing from about 0.1% to about 1.0% platinum andfrom about 0.1% to about 1.0% combined fluorine.

6. A process for the treatment of relatively light and heavy gasolinefractions, the heavier fraction forming more carbon than the lighterfraction during catalytic reforming, which comprises reforming theheavier gasoline fraction in the presence of hydrogen and aplatinumcontaining catalyst until the activity of the catalyst has beenlowered by the deposition of carbon thereon, then discontinuing thecontacting of the heavier fraction with said catalyst and substitutingthe lighter gasoline fraction therefor, reforming the lighter fractionin contact with said catalyst and in the presence of hydrogen until atleast a portion'of the carbon deposit has been removed resuming thereforming of 'the heavier gasoline fraction in contact with thecatalyst.

7. The process of claim 6 further characterized in thatsaid-catalystcomprisesplatinum and alumina. 8. The process of claim 6further characterized .in that said catalyst comprises platinum, aluminaand combined halogen.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Bland: Petroleum Processing, vol. '5, pages 351-460, April1950.

1. IN THE REFORMING OF A HYDROCARBON CHARGE STOCK BOILING APPROXIMATELYWITHIN THE GASOLINE RANGE AND HAVING A RELATIVELY HIGH END POINT IN THEPRESENCE OF HYDROGEN AND A CATALYST CONTAINING A METAL OF THE GROUPCONSISTING OF PLATINUM AND PALLADIUM, THE METHOD WHICH COMPRISESREFORMING SAID STOCK UNTIL THE CATALYST HAS LOST ACTIVITY, DISCONTINUINGTHE REFORMING OF SAID CHARGE STOCK AND SUBSTITUTING THEREFOR A NORMALLYLIQUID HYDROCARBON CHARGE STOCK OF LOWER END POINT, REFORMING SAIDLATTER STOCK IN THE PRESENCE OF HYDROGEN UNTIL AT LEAST A PORTION OF THELOST ACTIVITY HAS BEEN RESTORED, AND THEREAFTER DISCONTINUING THEREFORMING OF SAID LATTER STOCK AND RESUMING THE REFORMING OF SAID FIRSTSTOCK.